I stumbled onto this, turns out this is where Vari-prop is doing their UAV business. Perhaps I mis quoted Larry morgan about the high HP prop.
I wonder how many printer heads we would need to feed a 13b.

http://www.nwuav.com/fuel_injection.html

http://www.nwuav.com/variable_pitch_propellers.html


Paul Lamar

I am very impressed by the Ivoprop electric constant speed prop http://ivoprop.com/inflightmagnumodel.htm, at EAA chapter 55 we have two on 13Bs, one has been taxi tested, has anybody had problems with them.
Dave James

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Not recently to my knowledge. They seem to work OK on rotaries. The main problems occurred when they were mounted on a high torque pulse, direct drive, large displacement, air cooled aircraft engines, they would fail.

They are somewhat effective but they are really variable twist and not variable pitch. Variable twist as well as variable pitch is what the V22 Really needs.

See http://www.rotaryeng.net/VTOL.html

Paul Lamar

Does any one know the cause of this failure? Was it an accident?
Dave James

Carter Copter has an interesting technology for variable props.  Seems to be optimized for higher speeds (RPM).

http://www.cartercopters.com/propeller_system.html

Craig Taylor